Method of recovering clay used in bleaching petroleum products



C. W. STRATFORD.

METHOD OF RECOVERING CLAY USED IN BLEACHING PETROLEUM PRODUCTS. APPLICATION FILED MAR. 21, 1921.

1,408,656. atented Mar. 7, 1922.

TV/CIIIEIVEF'S [N V ENTOR mv/a Zsoll 754641.41 0: BY 1 N 4W2: WQMZ A TTORNE VS UNITED STATES PATENT OFFICE.

CHARLES WALCOTT STBA'IFORD, OF SAN FRANCISCO, CALIFORNIA.

Specification of Letters Patent.

Patented Mar. *7, 1922.

Application filed March 21, 1921. Serial No. 454,211.

To all whom it may concern:

Be it known that I, CHARLES WALOOTT S'rnATroRn, a citizen of the United States, residing at the city and county of San Francisco and State of California, have invented certain new and useful Improvements in Methods of Recovering Clay Used in Bleaching Petroleum Products, of which the following is a specification.

My invention relates in general to the art of bleaching or decolorizing petroleum products, and particularly to those methods or processes which involve the use of argillaceous material or bleaching earths, serving as a filtering agent for removing from said products the color bearing compounds, to the degree demanded by the trade.

F ullers earth, either a variety imported from England, or a domestic variety from Florida, known as F loridin fullers earth, is usually employed. But comparatively recently a deposit of good bleaching earth has been found in Death Valley, California. While the chemical analysis of this Death Valley clay is practically equivalent to that of Floridin fullers earth, its physical characteristics are quite different, in that it completely disintegrates when brought into contact with water, and, therefore, it can be used only in an extremely finely divided condition; and, also, it contains water-soluble and acid-soluble compounds which interfere with i the bleaching effect, and which must be removed by treatment with sulfuric or other acid.

In an application, filed contemporaneously herewith, Serial Number 454,210, I have disclosed a method of preparing this Death Valley clay for use as the filtering agent in bleaching or decolorizing petroleum products; and in another application, also filed contemporaneously herewith, Serial Number 454,209, I have disclosed a method of bleaching or decolorizing said products with said prepared clay; and though my present invention, which consists in a novel method of recovering said prepared and used or spent clay, is not confined to the use of this particular earth, it is, in a sense, dependent upon the use of clay in a finely divided condition from which all deleterious substances have been removed; and I have found, in practice, that Death Valley clay is very suit able for my present method, in that its use affords a convenient, economical and 'practical continuous method of recovering said spent clay for regeneration and use again in bleaching petroleum products.

The nature of my invention will be fully described in and ascertained by the following specification, in connection with the accompanying drawing in which the figure is a diagrammatic view of an apparatus suitable for carrying out my method.

Referring to the drawing-4 indicates a bin for the spent clay to be treated and recovered. Its contents is delivered through a line 2 to the first of a connected series of digesters 3, in which 4 indicates the agitating or mixing elements. 5 is a tank to contain naphtha, and 6 is a pump by which, through the line 7 the naphtha is delivered to the first of the digesters 3.

7 is a series of thickeners, in which 9 indicates the mixing element and 9' the distributing element. The last of the series of digesters or agitators 3 is connected with the first of the thickeners 8 by a line 10.

Each thickener is connected with the one succeeding by a line 11 leading from its bottom, through a pump 12, which discharges into the cascade chute 13 delivering into the thickener.

From the bottom of the last thickener leads a line 14 to a pump 15 which discharges through a line 16 into a clay drier 17 from which a line 18 leads to any suitable destination of the recovered clay.

19 is a storage tank for washing naphtha. A line 20 leads from this tank to and dis charges into the cascade chute 13 of the last thickener 8. From this thickener a line 21 leads back to and delivers into the cascade chute 13 of the preceding thickener, and from said last named thickener a line 22 leads back to and discharges into the first thickener. From the first thickener a line 23 leads either to a naphtha oil storage 24 or by a line 25 to a steam still 26. From this still the recovered oil is passed through av line 27 to a storage 28, while the distilled naphtha passes from the still through a condenser 29 and a line 30 to the washing naphtha storage'19.

From the top of the clay drier 17 leads a line 31 to a condenser 32 which by a line 33 delivers into a naphtha storage tank 34.

My method of recovering the spent clay,.

as carried out in this apparatus is as follows. The clay to be recovered, it is to be understood, is the spent clay after it has been used as a filtering agent in the bleach ing oi petroleum products; T his spent clay which contains some oil trom its previous use, is passed in a continuous stream from the clay bin 1, through the tine into the first ot the series ct digesters 3. the same time a stream of 1 aphtha from the tank 5 is supplied loy pump 6 through line 7 to said first digesterv Through the connected series cit digesters the clay with its oil content, and the naphtl'ia are passed in a continuous stream and are thoroughly agitated and m' From the last digester the miztture is discharged through the line into tl e first thicltener 8 and it thence passes, gradually increasing in density as a slinie from one thiclrener to the neat, as a continuous stream. through the connecting iincs 1L pumps and cade chutes 13.

From the last thiclrener the slime flows through the line it, pump 15 and line 16 into the clay drier ii. in this drier whatever naphtha accompanies the clay is dis tilled oil through the line 2th condenser 32, and line 33 into the storage 34h The dried chi is passed from the clay drier l'i through line 18 to Whatever destination may he provided tor the recovered clay.

A stream ct Washing naphtha from the storage 19 is passed through. the line 20' and delivered into the cascade chute l3 ot the last thiclrener This Washing naphtha {ions counter-cmrent to the tlou oi? the slimes, passing :t'rom the last thickener through the line 21, to the cascade chute ot the preceding thickener and from said thic ener through the line 26% to the it t thiclc ener, During this counter-current flow the Washing naphtha increases in oil content; and from the first thickener the oil-naphtha solution tlows through the line 533 either to the naphthanil storage or by the line to the steam still 26. in this still the napln that is distilled oil through condenser 29 hack into the Washing naphtha storage 19. The recovered. spent clay may be heated again tor its regeneration, utter which it may he used once more tor decoloriaing oils.

i hll steps ct my method conducted in the ap paratus are continuous,

claim l. The method ot recovering spent clay used in bleaching petroleum products which consists in passing a stream of spent clay and naphtha through a series of agitating means to min: them; passing a stream of said miitture through a series of thiclrening and washing means to reduce it to a slime; pass ing a stream of the slime to a drying means; and distiliing oit from the slime in drying, the naphtha content.

2. The method of recovering spent ciay used in bieaching petroleum products which consists in passing a stream ozt spent clay and naphtha through a series ot agitating means to mix; them; passing a stream. at said mixture through a series oit thickening and washing means to reduce it to a slime; pass ing a stream of naphtha through the series at thickening means counter-current to the stream of said mixture therethrough to Wash. out the oil content thereof; passing a stream of the slime to a drying means; and distilling oit from the slime in drying, the naphthe content.

3. The method oi? recovering spent clat used in bleaching petroleum products which consists in. passing a stream at spent clay and naphtha tl'lrough a series oi agitating means to mix them; passing a stream of said mixture through a series oi thicltening and Washing means to reduce it to a slime; pas it stream of naphtha through the series 0r thicltening means coimtercurrent to the stream at said mixture theretl'irougln to Wash out the oii content thereof; distilling the naphtha from said stream of oil and naphtha solution tor use again; passing a. stream or? the slime "from the thickening means to drying means; and distiliing ott trom the slime in drying, the naphtha con tent lfn tc ion u'l ereot l have signed my name to this specification htl 

